1. Technical Field
The present invention relates to a projector.
2. Related Art
It has been known that, in a projector that modulates and projects a light source beam output from a light source lamp with a liquid crystal light valve, flicker is suppressed by synchronization of the drive frequency of the alternately-current-driven light source lamp and the drive frequency of the liquid crystal light valve (for example, see Patent Document 1 (JP-A-2003-156798)). Further, it has been known that, for reduction of noise due to pulse for suppression of flicker superimposed on the drive waveform of the light source lamp, brightness of a video signal is reduced in a period in which the pulse is input (see Patent Document 2 (JP-A-2009-198886)).
However, it has been turned out that, if the projector is operated in a long period while the drive frequency of the light source lamp and the drive frequency of the liquid crystal light valve are synchronized, brightness ununiformity are caused in a specific position of a projected image.